PRIORITY ASSESSMENT FOR CONVERSION OF NORWAY SPRUCE FORESTS THROUGH INTRODUCTION OF BROADLEAF SPECIES

Serious damage to Norway spruce (Picea ies L. Karst) in Central and We stern Europe together with increasing preference for forests with natu ral species composition emphasise the necessity to convert Norway spru ce plantations on unsuitable sites and outside of its natural distribu tion. Site related priority assessment of Norway spruce replacement by Fagus sylvatica L., Quercus robur L., Acer pseudoplatanus L. and Frax inus excelsior L., respectively, was calculated using a geographical i nformation system for a management unit of 1248 ha in Upper Austria. T hree matrix overlays combining soil depth with soil skeleton and veget ation type with gleyification resulted in different risk categories fo r Norway spruce. Further matrix overlay with Norway spruce stocking in dicated sites with high conversion priority. Suitability indices of br oadleaf species were evaluated using indexing overlay, allowing to wei ght map attributes of seven site parameters. This calculation was done separately for each species studied. Combination of these suitability indices with the conversion priority of Norway spruce led to site-rel ated introduction priorities. The largest areas were found for Q. robu r, followed by F. sylvatica. The higher suitability of Q. robur compar ed to F. sylvatica was explained by its superior adaptation to the aci dic, shallow and partially gleyic soils in the area. The introduction of F. excelsior was generally not found advisable. The advantage of th is method over the use of classic site classification was seen in the direct implementation of current stand characteristics into the decisi on rules. (C) 1998 Published by Elsevier Science B.V.